US3927869A - Multiscrew extruder - Google Patents

Multiscrew extruder Download PDF

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Publication number
US3927869A
US3927869A US400059A US40005973A US3927869A US 3927869 A US3927869 A US 3927869A US 400059 A US400059 A US 400059A US 40005973 A US40005973 A US 40005973A US 3927869 A US3927869 A US 3927869A
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US
United States
Prior art keywords
chambers
recesses
housing
recess
improvement defined
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US400059A
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English (en)
Inventor
Wilhelm Hanslik
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mannesmann Demag Krauss Maffei GmbH
Original Assignee
Krauss Maffei AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Krauss Maffei AG filed Critical Krauss Maffei AG
Application granted granted Critical
Publication of US3927869A publication Critical patent/US3927869A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
    • B29B7/00—Mixing; Kneading
    • B29B7/30—Mixing; Kneading continuous, with mechanical mixing or kneading devices
    • B29B7/34—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices
    • B29B7/38—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary
    • B29B7/46—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft
    • B29B7/48—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft with intermeshing devices, e.g. screws
    • B29B7/486—Mixing; Kneading continuous, with mechanical mixing or kneading devices with movable mixing or kneading devices rotary with more than one shaft with intermeshing devices, e.g. screws with screws surrounded by a casing provided with grooves or cavities
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
    • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
    • B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
    • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
    • B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
    • B29C48/41—Intermeshing counter-rotating screws
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
    • B29C48/395—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders
    • B29C48/40—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die using screws surrounded by a cooperating barrel, e.g. single screw extruders using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
    • B29C48/435—Sub-screws
    • B29C48/44—Planetary screws
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/36—Means for plasticising or homogenising the moulding material or forcing it through the nozzle or die
    • B29C48/50—Details of extruders
    • B29C48/68—Barrels or cylinders
    • B29C48/685—Barrels or cylinders characterised by their inner surfaces, e.g. having grooves, projections or threads
    • B29C48/686—Barrels or cylinders characterised by their inner surfaces, e.g. having grooves, projections or threads having grooves or cavities

Definitions

  • ABSTRACT [30] Foreign Application Priority Data
  • the recesses designed to build up a counterthrust, lie in regions diametrically [5 References Cited opposite the entrance throat or are more or less symmetrically distributed about these regions.
  • MULTISCREW EXTRUDER BACKGROUND OF THE INVENTION more driven feed screws, extending parallel to the axis of a common housing within respective cylindrical chambers thereof, mesh with one another in one or more interchamber passages whose width is less than the chamber diameter.
  • Two such counterrotating feed screws in mesh with each other define in their interchamber passage an entrance throat into which the plastic mass moving toward the discharge end of the housing is frictionally entrained so as to produce a local increase in pressure. That pressure, acting upon the cores of the feed screws, gives rise to radially outward lateral thrusts which must be absorbed by the respectivechamber walls.
  • the feed screws in the housing are subject .to increased wear, especially in the high-pressure region adjacent the discharge or nozzle end of the extruder housing.
  • the general object of my present invention is to provide means in such an extruder for counteracting the aforementioned lateral thrusts to avoid the disadvantages enumerated above.
  • a more particular object is to facilitate the lubrica tion of the contact surface between housing and feed screw around the periphery of the latter.
  • each housing chamber should have a recess or a pair of recesses at the locations described. If, however, a central screw meshes with two or more planetary screws symmetrically disposed therearound, the central screw is not subjected to lateral thrusts so that only the'chambers for the planetary screws need to be provided with such recesses.
  • FIG. 1 shows, in a cross-sectional view taken near its discharge end, an extruder with dual feed screws embodying my invention
  • FIGS. 2 and 3 are views similar to FIG. 1, illustrating two modifications
  • FIG. 4 is an axial sectional view of the forward part of an extruder, taken on the line IV IV of FIG. 3;
  • FIG. 5 is a cross-sectional view similar to FIGS. 1 3, drawn to the same scale and showing an extruder with a central screw driving several planetary screws.
  • FIGS. 1 4 I have shown the forward part of the housing 1 of an extruder adapted to be used, for example, to feed a thermoplastic mass into a mold cavity of an injectionmolding machine.
  • Housing 1 has two cylindrical chambers 4 and 5 equispaced from the housing axis to accommodate' a pair of counterrotating-feed screws 2 and 3 driven by a motor (not shown).
  • the screws are jour naled in the housing with interposition of nonillustrated thrust bearings at their rear extremities to take up the reaction force of a flowable mass of thermoplastic material which is continuously advanced toward a nozzle (not shown) at the front end of the housing; to keep the plastic material in its liquefied state, the housing may be heated as is well known per se.
  • the helical threads of screws 2 and 3 intermesh within a passage 8 through which the two chambers 4 and 5 communicate with each other, this passage being spanned by a common chord of two intersecting circular outlines of these chambers.
  • a small transverse gap It exists between the outer periphery of one screw (e.g. the edge 12 of the web of screw (2) and the peripheral surface of the core of the other screw (as illustrated at 13 for the core 7); other, longitudinal gaps are present between the flanks of the meshing screw threads, their widths being determined by the relative width of the web, the pitch angle and the number of interleaved threads.
  • the lower half of passage 8 constitutes its entrance 'side or throat 14 whereas the upper half forms its exit side 15.
  • the plastic mass frictionally entrained by the threads 'of one screw is prevented by the blocking action of the threads of the other screw from rotating therewith about the screw axis, yet a certain pressure rise occurs in the throat 14 which tends to drive the two screws apart along axial planes l6 and 16a generally including an angle a on the order of 20 with a common axial plane 11 of the two screws.
  • the chamber diameter slightly exceeds the screw diameter to provide a narrow peripheral clearance into which the plastic mass can penetrate to form a thin lubricating film.
  • the width of this clearance depends on such factors as rotary speed, pitch, relative web width, pressure gradient, and viscosity or flowability of the plastic working medium.
  • the clearance should be so narrow as not to cause an appreciable pressure loss and to maintain a substantially even temperature profile throughout the crosssection of each chamber.
  • each of these chambers with a respectiveaxially extending shallow peripheral recess 17,- 17a (FIG. 1), bisected by the corresponding thrust plane 16, 16a, or with a pair of such recesses 18, 18" and 18a, 18a? symmetrically disposed with reference to that plane (FIG. 2).
  • These recesses serve as receptacles for working medium under pressure which opposes the radially outward lateral force exerted by the plastic mass in throat 14.
  • the recesses also constitute lubricant reservoirs and help reduce the shear forces which act upon the plastic mass; the reduction in shear forces can be enhanced by extending the recesses, as shown in FIGS. 3 at 19, 19" and 19a, 19a, toward the passage 8 while ending them short of that passage to ensure proper guidance for the feed screws.
  • the extended recesses may reach beyond a plane 20, 20a perpendicular to their respective plane of symmetry 16, 16a, tenninating along boundary lines which are peripherallyspaced from that plane by up to about 120.
  • FIGS. 1 3 extend with constant depth practically to the end of chambers 4 and 5, spanning a multiplicity of turns of the associated screw threads.
  • the cross-sections of the recesses "shown in FIGS. 1 and 3 are generally crescent-shaped, with a more or less tangential fairing of their sides into the cylindrical chamber periphery.
  • the outer curvature of the crescent is preferably circular, for simplicity of manufacture, though thisis not critical.
  • the recesses need" notbe continuous over the entire length of the housing portion shown in FIG. 4 but could be longitudinally subdivided into shorter sections.
  • the centrally disposed recess 17 or 17a may also be combined with a pairof laterally offset recesses 18, 18" or 18a, 18a" (with or without extensions as shown in FIGS. 3 and 2) in a single housing; in such a case the peripherally juxtaposed recesses may be fully separated or may merge into one another.
  • FIG. I have illustrated a modified extruder whose housing 101 has a central chamber 102 and three satellite chambers 102a, 102b, 1020 communicating therewith in the aforedescribed manner, these chambers accommodating a central screw 103 rotating in one sense (here counterclockwise) and three satellite screws 103a, 103b, 1030 rotating in the opposite sense (here clockwise).
  • the satellite chambers are provided with longitudinal recesses 1 17a, 1 17b, 1 17c at locations diametrically opposite the entrance throats of the passages 108a, l08b, 1086 through which these chambers communicate with the central chamber 102. As explained above, there is no need for providing any such recesses at the latter chamber.
  • an extruder for thermoplastic materials comprising a housing witha plurality of axially extending cylindrical chambers intercommunicating through a passage of a width less than the chamber diameter, and a like plurality of feed screws rotatable to drive a plastic mass in said chambers toward a discharge end of the housing, said feed screws intermeshing with one another at said passage and defining an entrance side and an exit side for said passage, the improvement wherein said housing is provided in the vicinity of said discharge end with at least one axially extending shallow peripheral recess in each of at least two of said chambers at a location remote from the entrance side of said passage for counteracting a lateral thrust exerted by said mass upon the corresponding feed screw, said recess being a single continuous groove spanning a multiplicity of turns of the threads of said corresponding feed screw and being of such shape and dimension that the thermoplastic material being extruded will flow easily into and out of said recess and will not lodge therein.
  • each of said recesses terminates on a line .peripherally spaced fromsaid first-mentioned plane by substantially 8.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)
US400059A 1972-09-27 1973-09-24 Multiscrew extruder Expired - Lifetime US3927869A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19722247286 DE2247286A1 (de) 1972-09-27 1972-09-27 Schneckenpresse fuer thermoplastische kunststoffe od. dgl

Publications (1)

Publication Number Publication Date
US3927869A true US3927869A (en) 1975-12-23

Family

ID=5857474

Family Applications (1)

Application Number Title Priority Date Filing Date
US400059A Expired - Lifetime US3927869A (en) 1972-09-27 1973-09-24 Multiscrew extruder

Country Status (9)

Country Link
US (1) US3927869A (sv)
JP (1) JPS4972357A (sv)
AT (1) AT334612B (sv)
BR (1) BR7307490D0 (sv)
CH (1) CH563862A5 (sv)
DE (1) DE2247286A1 (sv)
FR (1) FR2200105B3 (sv)
GB (1) GB1440100A (sv)
IT (1) IT996199B (sv)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4556324A (en) * 1984-05-01 1985-12-03 E. I. Du Pont De Nemours And Company Apparatus for forming films of constant thickness
US6270245B1 (en) * 1996-11-21 2001-08-07 Clextral Extrusion machine barrel having a three-lobe bore, and liner therefor
EP1475536A2 (en) * 2003-05-08 2004-11-10 Automotive Motion Technology Limited Improvements in or relating to pumps
GB2422327A (en) * 2005-01-25 2006-07-26 George Martin Gale Thermoplastic laboratory mixer

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2588888A (en) * 1949-02-08 1952-03-11 Laval Steam Turbine Co Pump
US3291061A (en) * 1963-07-23 1966-12-13 Kosaka Kenkyusho Ltd Screw pump or hydraulic screw motor
US3640669A (en) * 1968-11-18 1972-02-08 Dorplastex Ag Multiple-screw extruder

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2588888A (en) * 1949-02-08 1952-03-11 Laval Steam Turbine Co Pump
US3291061A (en) * 1963-07-23 1966-12-13 Kosaka Kenkyusho Ltd Screw pump or hydraulic screw motor
US3640669A (en) * 1968-11-18 1972-02-08 Dorplastex Ag Multiple-screw extruder

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4556324A (en) * 1984-05-01 1985-12-03 E. I. Du Pont De Nemours And Company Apparatus for forming films of constant thickness
US6270245B1 (en) * 1996-11-21 2001-08-07 Clextral Extrusion machine barrel having a three-lobe bore, and liner therefor
EP1475536A2 (en) * 2003-05-08 2004-11-10 Automotive Motion Technology Limited Improvements in or relating to pumps
US20040228745A1 (en) * 2003-05-08 2004-11-18 Beaven Robert William Pumps
EP1475536A3 (en) * 2003-05-08 2005-05-25 Automotive Motion Technology Limited Improvements in or relating to pumps
US7275921B2 (en) 2003-05-08 2007-10-02 Automotive Motion Technology Ltd. Pumps
GB2422327A (en) * 2005-01-25 2006-07-26 George Martin Gale Thermoplastic laboratory mixer

Also Published As

Publication number Publication date
BR7307490D0 (pt) 1974-09-05
DE2247286A1 (de) 1974-03-28
CH563862A5 (sv) 1975-07-15
JPS4972357A (sv) 1974-07-12
FR2200105A1 (sv) 1974-04-19
IT996199B (it) 1975-12-10
ATA630873A (de) 1976-05-15
AT334612B (de) 1976-01-25
FR2200105B3 (sv) 1976-07-30
GB1440100A (en) 1976-06-23

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